Complex Specific Operations

NUM1  +:  NUM2  ->  NUM3
NUM1  -:  NUM2  ->  NUM3
    These two operators are the basic way of creating complex numbers.
    Effectively, they both multiply their second argument by "i" (the
    positive square root of -1), and then either add the result to (+:)
    or subtract the result from (-:) the first argument.

+: NUM1  ->  NUM2
-: NUM1  ->  NUM2
    As prefix operators, +: and -: are equivalent to unary_+:(NUM1) and
    unary_-:(NUM1) respectively.

unary_+:(NUM1)  ->  NUM2
unary_-:(NUM1)  ->  NUM2
    Single-argument versions of +: and -:, which multiply their argument
    by i and -i respectively.

conjugate(NUM1) -> NUM2
    Returns the complex conjugate of its argument. The conjugate of a
    real number is itself, while for a complex number it is

        realpart(NUM1) -: imagpart(NUM1)

destcomplex(NUM) -> (REALPART, IMAGPART)
realpart(NUM)    -> REALPART
imagpart(NUM)    -> IMAGPART
    These procedures return the real and imaginary parts of a complex
    number, either together (-destcomplex-), or separately (-realpart-
    and -imagpart-). When NUM is real, then REALPART = NUM, and a zero
    of the same type as NUM is returned for IMAGPART.